#include "my_stdio.h"

#include <string.h>

#include <stdlib.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <fcntl.h>

#include <unistd.h>

mFILE * mfopen(const char * filename,
    const char * mode) {
    int fd = -1;
    if (strcmp(mode, "r") == 0) {
        fd = open(filename, O_RDONLY);
    } else if (strcmp(mode, "w") == 0) {
        fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC, 0666);
    } else if (strcmp(mode, "a") == 0) {
        fd = open(filename, O_CREAT | O_WRONLY | O_APPEND, 0666);
    }
    if (fd < 0) return NULL;
    mFILE * mf = (mFILE * ) malloc(sizeof(mFILE));
    if (!mf) {
        close(fd);
        return NULL;
    }
    mf -> fileno = fd;
    mf -> flag = FLUSH_LINE;
    mf -> size = 0;
    mf -> cap = SIZE;
    return mf;
}
void mfflush(mFILE * stream) {
    if (stream -> size > 0) {
        // 写到内核文件的文件缓冲区中!
        write(stream -> fileno, stream -> outbuffer, stream -> size);
        // 刷新到外设
        fsync(stream -> fileno);
        stream -> size = 0;
    }
}
int mfwrite(const void * ptr, int num, mFILE * stream) {
    // 1. 拷贝
    memcpy(stream -> outbuffer + stream -> size, ptr, num);
    stream -> size += num;
    // 2. 检测是否要刷新
    if (stream -> flag == FLUSH_LINE && stream -> size > 0 && stream ->outbuffer[stream -> size - 1] == '\n') {
        mfflush(stream);
    }
    return num;
}
void mfclose(mFILE * stream) {
    if (stream -> size > 0) {
        mfflush(stream);
    }
    close(stream -> fileno);
}
